The invention relates to an encapsulation of a photovoltaic element such as a solar cell or solar cell module, the free outer surface at least of said element being covered by a transparent protective film comprising a dielectric silicon compound, and to a method for implementation of an appropriate encapsulation.
Solar cells, or modules or panels consisting thereof, for photovoltaic current generation are used both indoors and outdoors. Their main application is, however, employment in the open, for example in energy generation for single-family houses, pumps, refrigeration units, boats, etc. This open-air use subjects them to a variety of disturbing factors, for example weather, dust, dirt, etc. For this reason the current-generating and -discharging components and the connections between the individual cells must be protected from such effects. A known method, for example, is to encapsulate solar cells by adhering special glass or quartz glass sheets, transparent plastic, or plastic-coated metal foils onto the rear of the cells. These covering panels between which the solar cell lies are surrounded by a frame and sealed. Between the covering panels and the cells transparent organic materials can be inserted in addition. The material must be selected on the basis of the following considerations:
good optical properties (translucency, refractive index), which must not be susceptible to degradation by sunlight,
mechanical and thermal properties (breaking strength, impact resistance, temperature resistance, thermal expansion, tightness)
resistance to mechanical and chemical effects (erosion, corrosion, impurities),
resistance to all weather conditions.
Appropriate encapsulation techniques have considerable drawbacks resulting both from the large number of different materials used that come into contact with one another, and from expensive and complicated production technologies. Additional problems arise when the size of the surface to be encapsulated or sealed increases. Since compromises also have to be made as regards material selection, there is a risk of glass breakage or lack of resistance by the organic material to long-term light and environmental effects. In addition, the varying thermal properties of the adjacent materials can cause breakage and damage in the photovoltaic cells and modules in the event the latter are used under high temperature fluctuations.